Small Ruminant Parasitology Quiz

Small Ruminant Parasitology

• Tail up = Goat, Tail down = Sheep
• Parasitic Gastrointestinal Disease Objectives: Students will be able to employ best deworming strategies for small ruminants, summarize the pathology associated with common gastrointestinal parasites, and develop an appropriate diagnostic and treatment plan.

Gastrointestinal Nematodes of Small Ruminants

• Haemonchus contortus: A very pathogenic nematode.
• Telodorsagia circumcincta (formerly Ostertagia): Also a pathogenic nematode.
• Trichostrongylus axei: A nematode.
• Nematodirus spp.: A nematode.
• Cooperia spp.: A nematode.
• Abomasal Nematodes: These are the most pathogenic.
• Most Susceptible Animals: Young, periparturient (around birth), animals with fecal egg counts that go up during the last month of gestation, and immunocompromised animals.

Life Cycle of Gastrointestinal Nematodes

• Pre-patent Period: 3 weeks (ingestion of larvae – fecal excretion of eggs)
• Egg to Larvae: Summer: 4-10 days; Winter: 1-2 months; Can survive longer until environmental conditions are favorable
• Epizootiology: Life cycle of each GIN (Gastrointestinal Nematode) has 4 phases: (1) Symbiotic/Parasitic, (2) Contamination, (3) Free-living, (4) Infection. The organism must survive within the host; host defense depends on immune system, and age.

Contamination Factors

• Nutritional Status: Stress can lead to Hypobiosis, arresting development.
• Contamination Hallmark: Eggs passed in feces; factors affecting contamination magnitude include stocking rate, age, periparturient (around birth), elevated egg count, and season.

Haemonchus contortus (Haemonchosis)

• Description: "Barber pole" worm; coiling of white ovaries around blood-filled intestines.
• Feeding: Can consume 0.05mL of blood per day, and at peak infection, can consume 1/5 of an animal's blood volume daily.
• Clinical Signs: Anemia symptoms (lethargy, peripheral edema), pale mucous membranes, and pale mucous membranes especially visible at arrow in body region.

Ostertagia / Telodorsagia

• Species: Cattle, South American camelids, Sheep, and Goats
• Pathogenic effect: Severe abomasitis; impaired nutrient digestion in sheep and goats.
• Pathogenesis Types: Two types (I & II). Type I: characterized by the parasite completing its entire life cycle, heavy fecal eggs. Type II is identical to Type I until L4 enters parietal cell, improved weather leads to emergence from hypobiosis.

Important Intestinal Nematodes (Reference/General)

• Cooperia: Most common intestinal worm in cattle; creates erosive mucosal lesions within the small intestine.
• Ascaris: "Traveling worm" migrates from intestine -> liver -> lungs -> intestine; focal scarring in the liver (white spots).
• Nematodirus: Common in confined camelids; resistant to ivermectin.
• Oesophagostomum: Large intestine; nodular abscess formation within large intestinal wall.
• Trichuris: Whipworms; bloody diarrhea.
• Important Intestinal Worm Considerations: Pigs on dirt lots.

Nematodes: Basics of Treatment

• Anthelmintic Therapy: includes blood or plasma transfusion, iron/B-vitamin supplementation, TLC (low competition), and high quality nutrition are needed.
• Imidazothiazoles/tetrahydropyrimidines: Levamisole, Morantel, Pyrantel.
• Macrocyclic Lactones: Ivermectin, Doramectin, Moxidectin.
• Benzimidazoles: Fenbendazole, Albendazole, Oxbendazole.
• Important Consideration: Fenbendazole can increase dosage 2-3X up to 10X for hypobiotic larvae.

Why Don't Dewormers Work?:

• Resistance: Some species create resistance to dewormers.
• Inappropriate Dose: Some species metabolize drugs quickly and require a different dosing regime than other animals.
• Treating the wrong parasite: The parasite being targeted may not be the cause of the problem.

Who to Deworm?

• Correct Dose: Goats metabolize drugs differently than other animals and may require higher doses.
• Withhold Feed: Benzimidazoles are best used by withholding feed for 12-24 hours.
• Combination Treatment: Use multiple dewormers in combination to reduce resistance. Avoid using long-range dewormers.
• Consult Veterinarian: Discuss treatment with a veterinarian if unsure or handling a large scale operation.

FAMACHA System

• Anemia Identification: Provides a system to identify anemic animals and score their severity of anemia, and to treat based on severity.
• Worm Burden: More pallor (lighter coloration) = greater worm burden.
• Limitations: Only appropriate for adult animals, increases labor significantly, and doesn't account for other causes of anemia.

Combination Deworming Strategy

• Additive Effect: Dewormers in combination have a greater effect than a single agent.
• Reduced Resistance: Deworming in combination can reduce resistant worm populations.
• Example: Drug #1 has 90% efficacy, Drug #2 has 90% efficacy; in combination they will remove 99% of the worms.

Anthelmintic Resistance - Detection

• Fecal Egg Count Reduction Test (FECRT): A test to determine the presence of resistant worms. Assess 10-15 animals at one time; collect feces immediately before and 10-14 days after treatment.
• Epg Levels: Animals must have a minimum of 150-200 eggs per gram (epg) before treatment.

Alternative Treatments

• Copper Oxide Wire Particles (COWP): Lodge in the abomasum and cause cuticle defects in adult worms.
• Nematophagus Fungi(Duddingtonia flagrans): Worm-eating fungi that are eaten by animals and kills worms in feces and reduces pasture contamination.

Coccidiosis

• Common Disease: A very common disease in young livestock
• Non-Worm Disease: Not a worm disease so different treatments are required.
• Pathogenesis: Fecal-oral transmission; oocytes infect enterocytes.
• Clinical Signs: Diarrhea, +/- hematochezia, anorexia, dehydration, weight loss, dull/puffy hair.
• Treatment: Supportive care is needed, such as intravenous fluids, B-complex vitamins, and blood transfusions. Anti-coccidial drugs such as Ionophores, decoquinate, and coccidiocidal agents are also used.

Coccidia - Control

• Separate Feed and Water: Separate feed and water from feces.
• Manage Maternal Source: Manage maternal source of oocysts.
• Adequate Bedding Changes: Ensure adequate bedding changes.
• Coccidiostatic/Coccidiocidal Drugs: Drugs such as Decoquinate and Amprolium are used.

Test your knowledge on the parasitology of small ruminants, focusing on gastrointestinal nematodes such as Haemonchus contortus and their impact on health. The quiz will cover deworming strategies, common parasites, and their life cycles. Prepare to explore diagnostic and treatment plans for affected animals.